Wakefulness level determination device, wakefulness level determination method, and computer readable storage medium

A wakefulness level determination method executed by a computer, the method comprising:

• detecting a heartbeat signal of a subject;
• calculating, using a processor, a first feature value from the heartbeat signal of the subject detected in a predetermined period of time during which the subject is assumed to be fully awake;
• estimating, using the processor, from the first feature value, a second feature value representing a feature value of the subject when not fully awake, on the basis of a predetermined correlation between the first feature value and the second feature value;
• setting, using the processor, as an index of a wakefulness level, a range from the first feature value to the second feature value;
• calculating, using the processor, a third feature value from another heartbeat signal of the subject;
• and
• determining, using the processor, a wakefulness level of the subject by comparing the third feature value with the index of the wakefulness level.

A non-transitory computer readable storage medium having stored therein a wakefulness level determination program causing a computer to execute a process comprising:

• detecting a heartbeat signal of a subject;
• calculating a first feature value from the heartbeat signal of the subject detected in a predetermined period of time during which the subject is assumed to be fully awake;
• estimating, from the first feature value, a second feature value representing a feature value of the subject when not fully awake, on the basis of a predetermined correlation between the first feature value and the second feature value;
• setting, as an index of a wakefulness level, a range from the first feature value to the second feature value;
• calculating a third feature value from another heartbeat signal of the subject;
• and
• determining a wakefulness level of the subject by comparing the third feature value with the index of the wakefulness level.